Sweetness of sweet protein thaumatin is more thermoresistant under acid conditions than under neutral or alkaline conditions

Kaneko, R Kitabatake, N

R. Kaneko et N. Kitabatake, Sweetness of sweet protein thaumatin is more thermoresistant under acid conditions than under neutral or alkaline conditions, BIOS BIOT B, 65(2), 2001, pp. 409-413

17

INGLESE

Article

Agricultural Chemistry","Biochemistry & Biophysics

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY

0916-8451 → ACNP

65

2

2001

409 - 413

ISI

0916-8451(200102)65:2<409:SOSPTI>2.0.ZU;2-A

Thermostability of thaumatin and mechanisms of thermoinactivation were exam ined at 80 degreesC in the pH range from 2 to 10. The sweetness of thaumati n disappeared on heating at pH above 7 for 15 min, but the sweetness remain ed even after heating at 80 degreesC for 4 h at pH 2. This indicated that t he sweet protein thaumatin is more thermoresistant under acid conditions th an under neutral or alkaline conditions. Prolonged heating of thaumatin und er acid conditions slowly reduced sweetness, and produced a heterogeneous p opulation of molecules, all of which was soluble and monomeric. The resulta nt molecules were clearly distinct from those generated by heating at pH ab ove 7. Hydrolysis of peptide bonds and other irreversible chemical reaction s slowly took place in the molecule heated under acid conditions, and it wo uld be, in part, a cause of thermoinactivation of thaumatin under acid cond itions. The thermostability of thaumatin and the mechanism of thermoinactiv ation were largely dependent on pH.